Cold forming apparatus



Feb, 26, 1957 c. CLEVENGER 2,782,663 cow FORMING APPARATUS Filed Sept. 1, 1955 3 Sheets-Sheet l INVENTOR. Carl L. Clan/anger His A/romey Feb. 26, 1957 c, CLEVENGER 2,782,663

COLD FORMING APPARATUS 5 Sheets-Sheet 2 Filed Sept. 1, 1955 INVENTOR. Car/ L. Cleve/7 gar fir

f His Afforney Feb 26, 11%? CLEV G R 'zfismw COLD FORMING APPARATUS 3 Sheets-Sheet 3 Filed Sept. 1, 1955 Fig. 5

INVENTOR. Carl L. Cleve/7 statfis 2,782,663 COLD FORMING APPARATUS Carl L. Clevenger, Anderson, Ind., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware These shafts are generally of rather substantial diameter and of relatively hard material and must be formed within close dimensional limits if they are to permit other parts of the starting mechanism with which they are associated, to function properly. The apparatus according to my invention, when used, will form at least three circumferentially disposed helical grooves in a shaft which are located and dimensioned within tolerances which will permit the shaft to be used with a sleeve which has internal splines formed to ride without galling or binding in the grooves of the shaft. A sleeve of the type herein contemplated is shown in application, Serial No. 532,076, concurrently filed herewith and assigned to the assignee of the present invention.

It is to be appreciated that a high deforming pressure will be necessary if shafts of the type herein described are to be cold formed. These high deforming pressures coupledwith the high precision requirements necessary to form a satisfactory starter shaft have heretofore precluded the use of cold forming methods and apparatus to objects of the character described.

It is an object, therefore, of the present invention to cold form the helical grooves in a shaft for a starting motor of an automotive vehicle.

It is another object of the present invention to provide the helical grooves of a starter shaft with a square end which acts as a stop to limit the travel of a sleeve thereon.

A further object of the present invention is to provide an adjustment for the forming rolls in an apparatus that is adapted to cold form helical spiralled grooves in a starter shaft so the grooves formed by the apparatus will be within the required dimensional tolerances.

It is another object of the present invention to provide an apparatus which will cold form a helical groove in a starter shaft. This object is materialized by orientating at least three roller segments at an angle to the axis of the shaft that is operated upon and to provide an adjustment to precisely locate the rolls relative to each other and to a common center-line so the helical grooves formed in the shaft will be within permissible dimensional tolerances.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred embodiments of the present invention are clearly shown.

In the drawings:

Figure 1 diagrammatically shows the cold forming apparatus according to the present invention.

Figure 2, in perspective, shows a portion of the shaft which has been cold formed by the apparatus shown in Figure 1.

Figure 3 is a plan view of a portion of the cold forming apparatus in Figure 1 and showing the orientation of the roller segments and the pivotal mountings therefor.

Figure 4 is a sectional View showing a portion of the apparatus along line 4-4 in Figure 3.

Figure 5 is a sectional view showing a portion of the apparatus along line 55 in Figure 3 and showing the means for applying pressures on the roller segments for cold forming the shaft.

In the drawings and in Figures 1 and 5 particularly the apparatus shown for forming the helical grooves in a starter shaft 22includes a pressure applying means 24, a die holder 26 and a means 28 for ejecting the cold formed shaft from the die holder 26. p

The die holder 26, in the preferred embodiment of the present invention, includes a Y-shaped frame 30 which forms a pillow block for the segment rollers 32. The pillow block 30 is preferably formed of a plurality of sections which have mating faces. The sections are held in alignment with each other by the keys 34 and suitably located bolts 31. The pillow block 30, when assembled, has three radially disposed slots 38 extending therethrough. The slots 38 are oreinted in the block 30 at an angle relative to a common center line AA which is perpendicular to the flat base of block 30. The block 30 is also provided with a plurality of bores 40. These bores 40 are arranged in block 30 equidistantly from the center line A-A and are disposed perpendicular to the walls of the slots 38 to provide bearings for the journal of a shaft 42 which will be hereinafter described.

The shafts 42 are provided with ends 44-and 46 which are adapted to be journalled in the bores 40. These shafts 42 are provided with an intermediate portion 48 which is disposed between and eccentric to portions 44 and 46.

The portion 48 is sized to be received in a bore 49 in the roller segments 32 and provides an adjustable bearing pivot therefor. The eccentric portion 48, when adjustably rotated relative to block 30, will cause the roll seg- 'ments 32 to move relative to the center line A-A of block 30. This movement of the segment 32 will cause the depth of the grooves in'the shaft to be predeterminately varied. I r

The shaft 42 is held in a nonrotative position by a'locking means which may include a calibrated dial .50 and a fastening bolt 52 which is-threaded into block '30:. To facilitate the rotation of the shaft 42 in' the 'b'o'res40, a; squared end 54 on shaft 42 is provided. This squared end 54 will permit a conventional wrench to be utilized to adjust the position of the roll segments 32.

As heretofore indicated, the roll segments 32 are pivotally mounted through eccentric portion 48 in pillow block 30. These roll segments 32 are provided with a curved surface 56 which has a predetermined contour so that the ridge 58 which is located thereon will be at a constant distance from the center line A-A when the segments 32 are rotated. The rotation of the segments 32 is accomplished by the downward movement of the pressure applying means 24 which may be suitably secured in a punch press, not shown, and arranged to engage the curved lug surface 60 on the top edge of the segments 38. The curvature of lug 60 is preferably arranged so that the lug 62 of the pressure applying means 24 will ride thereon and cause the three roller segments 38 to have a simultaneously downward movement. The roller segments 32 are disposed in the inclined slots 38 to impart a rotative movement to the shaft 22 as the shaft is forced downward between segments 32. After the shaft has been forced downwardly, it will bear against the ejecting means 28 which is here shown as an air cylinder. During the down wardmovementof the-.roll segments 32', the shaft 22 will be rotated and the helical grooves will be formed inthe surface thereof. These grooves, because of the shape of the ridge 58, on roller segments 32, will have a predeterminedshape and preferably willterminate in a squared root end 64. After the shaft has been formed duringzthe downward movement, the ejecting means will cause the shaft 22 to be vertically moved-upwardly. and simultaneously cause the roller segments 32 to move upwardlyand separate so that the operation may be again performed on another shaft.

The squared disposed root portion 64 of the grooves 20 will act as a stop means for the inward facingisplines ofia sleeve, not shown, to limit the travelof the sleeve in one direction along the shaft. It is apparent from the above, that, if more than three helical grooves are desired in a shaft, a greater number of roll segments must be positionedin the pillow block. The adjustment of these roll segments 32 may be accomplished as previously set forth. Further, it is apparent that, if satisfactory grooves are to be cold formed in the starter shaft, curvature 56 of the ridges 58 and the movement of the roller segments 32 must be closely controlled so the ridges 58 will be properly oriented and simultaneously move as a group toward the shaft which is oriented along the center line A--A. The control of the movement of roller segments'32'is accomplished by providing the pressure applying means on the end of a ram of a suitable punch press, not shown. This pressure applying means24 will cause the roll segments 32 to move simultaneously so that the helical grooveswill be properly oriented on the peripheries of the shaft surface. It is to be further appreciated that severe deforming stresses will be present if the type of helical grooves herein contemplated are cold formed. To compensate for these stresses, the pillow block is preferably formed of heavy metal material which will withstand the stress of the application involved.

While the embodiments of the present invention as herein disclosed, constitute preferred forms, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. An apparatus for forming at least three helical splines: on. a shaft comprising; a pillow block. having at least three slots radially arranged about a common. center line, said slots each having walls extending through said block at. an. angle to said center line, a plurality of bores arranged in said block and communicatingwith said slots to form bearing in the walls of said slots, said bores being equidistantly spaced from said center line and perpendicularly extending from the walls of. said slots, at least three die segments constructed and arranged to be pivotally mounted in'said slots, each of said segments having, a bore extending tlie'rethrough and having a ridge on a curved surfacethereof disposed .equidistantly from said center line when the bores in said die segments are aligned with the respective bores in said block, and a means for pivotally mounting said die segments on the slots of said block, said means including; a plurality of pivot pins each having axially spaced and aligned journal portions and having a bearing portion intermediate said journal portion eccentrically disposed relative to said journal portions, and receivable in the bores of said segments for providing a pivot therefor, and an adjustment and locking means on one end of each pin for rotating the eccentric bearing portions relative to said block and thereby adjustably movingsaid segment relative to said center'line.

2. An apparatus for forming at least three helical splines on a shaft, comprising; a pillow block having at least three slots radially arranged about a common center line and extending through said block at angle to said center line, a plurality of bores arranged in said block to communicate with said slots to form bearings in the walls of the slots, said bores being equidistantly spaced from said center line and perpendicularly extending from said walls,.at least three die segments constructed and arranged to be pivotally mounted in said slots, each of said segments having; a bore extending therethrough, a ridge on a curve surface thereof, and a curved lug partly defined by a plane perpendicular to said center line, said segments being arranged in saidslots so the ridges on said segments are equidistantly spaced from said center line when the bores in said die segments are in alignment with the respective bores in the slot wherein the segment is positioned, a means for pivotally mounting said die segments in the slots; said means including; a plurality of pivot pins-each having axially spaced-and aligned journal portions and a bearing portion intermediate said journal portion eccentrically disposed relative to said journal portions, said eccentric journal portion being receivable in the bores of said segments for providing a pivot therefor, and an adjustment and locking means on one end of each pin for rotating the eccentric bearing portions relative to said blockandthereby adjustably moving said segment relative to said center line, and a press ram adapted to engage the curved lug of said segments for moving the ridges thereon into engagement with a shaft when said shaft is positioned betweensaid segments along saidcenter line.

References Cited in the file of this patent UNITED STATES PATENTS Buschick et al Iunev 12,1888 

